A method of assembling semiconductor devices with semiconductor dies of alternative different configurations uses the same substrate panel. The dies of the selected configuration are placed in an array, mounted, and connected to internal electrical contact pads on a first face of the panel using main fiducial markings and an array of subsidiary fiducial markings corresponding universally to arrays of semiconductor dies of the different alternative configurations. The pitch of the subsidiary fiducial markings is equal to the spacing between adjacent rows of the internal electrical contact pads on the panel and is a sub-multiple of the pitch of the array of dies.